Tobi is obito. obito gave kakashi his left eye on there last mission together, just before he died.
Tobi is not Madara Uchiha. He is Obito Uchiha, whose right eye is his original Mangekyo Sharingan eye. His other eye is the eternal one, considering he can evolve it to the Rinnegan form, it's most likely to be one of Madara's.
Tobi wields the Makengo Sharingan.
Sharingan eyes can be implanted into other people. Obito Uchiha gave his original left Sharingan eye to Kakashi before his apparant death. He manages to replace it with another one, the source isn't revealed. It possibly came from the time of the Uchiha massacre, as Tobi was in the vicinity and spoke to Itachi at the time. One other possible source is Madara Uchiha, who had on eye remaining at the time he took Obito in and saved him from his injuries. Tobi was forced to use the Izanagi technique during his fight with Konan, at the cost of this replacement eye. However soon after he replaced it with Nagato's Rinnegan, so right now he only has his original sharingan right eye.
Tobi is a character from the manga and anime series Naruto. He is typically depicted as wearing a mask with a single hole for his right eye, covering his left eye with his hair. He is often seen wearing a black cloak with red clouds on it.
After Konan died Madara (Tobi) found Nagato's body and he transplanted Nagato's rinnegan into his left eye.
Obito is a friend of Kakashi and Rin, pupil of Minato, he is an Uchiha Clan Member, he died in Kakashi Chronicles and gave Kakashi his left Sharingan eye, later on, Kakashi is an adult in his 20's, he's a Sensei, and Obito is dead, or is he? Tobi of the Akatsuki is new to the team and lacks heart and strength, he is bad for bribing someone to take off his mask and show it to them if they do something for him, his mask covers only his left eye, HMM?, in a Naruto Shippuden Manga Chapter I read he had the Sharingan Eye in his right eye, but not his left, his hair is a resemblance of Obito's and notice Tobi's name, Obito has the same without the extra "O", read it back words, you'll get it eventually. So I'm saying Obito is Tobi of the Akatsuki.
Tobi is not in one eye, but possess something very awesome so don't read on if you dont want me to spoil it................................... Tobi's is really Madara Uchiha (one of the 2 founders of the hidden leaf village (konoha) his eyes are really the Sharingan .
Tobi is MADARA UCHIHA. OBITO IS DEAD!!! HE WAS CRUSHED UNDER A ROCK!!! HE IS GONE FOREVER!!!!!Different person: I think Tobi is Madara and Obito. . .he is three in one! Why else would Tobi only have one eye! He gave his other sharingan to Kakashi. They wouldn't just bring up some random Uchiha and then just kill him off in his second episode. He has a perpose other than giving Kakashi his eye. . .right!Tobi in mandara ,obito is dead, the reason Tobi clothes is half armor is because he has deep wounds from the battle with Hashirama Senju and he still has is eyes but lost one by using inzagi to much from the battle with konan after konan got defeated but not killed Tobi went to yahiko and nagito grave to get the rinnegan and now his left eye is the rinnegan and right is sharingan. :) the first answers got pwned.
No, if you read the latest manga like on Mangareader.net, you'll see that Kabuto revives Madara and if Tobi was Madara, he should be dead. Tobi is most likely Obito, Kakashi's lost teammate, because Obito gave his left eye to Kakashi and the mask only reveals his right eye. Tobi soon replaces his right eye with the rinnegan which he takes from Nagato's dead body and he kills Konan.
Tobi and Obito are absolutely not the same person(honestly we have no idea who tobi is, but he is not Madara).It was "revealed" in the episode where Tobi met Sasuke that Tobi is actually Uchiha Madara(but is later revealed he is not as Madara is brought back to life with Edo Tensei.),because he knows the reason why itachi wiped out the entire uchiha clan( which Tobi helped Itachi with),which happened after Obito was dead.The reason why people insist that Tobi and obito are the same person is because of the resemblance it their names.Possibly,because kakashi's sharingan(left eye) from obito, has power that is whatever he sees it can transfer anything in other dimension/place , and just like Tobi can travel anywhere by dimension by using his sharingan (right eye). They're both using the same sharingan and powers ('cos it come to only one person, obito, and obito himself is Tobi(Possibly)). Kakashi (in manga/anime )can't actually do what Madara/Tobi/obito do 'cos he is not original uchiha(he can access the powers of sharingan but can't deactivate it, which is why he keeps it covered), and only true uchiha can perfect the power of their own sharingan(This is wrong becausethere is plenty of proof towards it but plenty against as kakashi is able to awaken Mangyeko sharingan).
_____Spoiler_____ Pein is the "leader" of the Akatsuki. But the founder of it was Madara, who is Tobi. Many people think Tobi is Otobi because of his eye, but he is not. Otobi was clearly killed. ~Lexi
In the Kakashi Chronicles it never did show Obito die, it just showed a huge boulder falling where he was, he could have been moved by a extremely fast ninja, or he didn't die by being crushed (not likely). Also, the war was going on between the Hidden Stone and Hidden Grass, which means any one of three akaski could have gotten him probably Zetsu). Plus it showed his sharingan in chapter 364, and he would be the only Uchia who Itiachi couldn't kill because he was already supposedley dead. And, it probably true, because why would he create Obito and Tobi if Obito died and Tobi is an idiot? Here is one(1) proof , kakashi's sharingan(left eye) from obito, has power that is whatever he sees it can transfer anything in other dimension/place , and just like madara/tobi/obito can travel anywhere by dimension by using his sharingan (right eye). They're both using the same sharingan and powers ('cos it come to only one person, obito, and obito himself is madara/tobi). Kakashi (in manga/anime )can't actually do what Madara/tobi/obito do 'cos he is not original uchiha, and only true uchiha can perfect the power of their own sharingan.